The present invention relates to a composite-motion drive unit employing an electromagnet and another drive source for driving two members independently of each other, and more particularly to an article distributing and supplying device in a combinatorial weighing apparatus employing such a composite-motion drive unit.
Combinatorial weighing apparatus for automatically weighing articles of merchandise have a central vibratable distributing and supplying device for substantially uniformly distributing and supplying the articles which have been charged from an upper source to a plurality of weighing machines or pool hoppers associated respectively therewith, the weighing machines being arranged in a circular pattern around the central distributing and supplying device. Where the articles to be weighed are pieces which tend to cling together and do not flow smoothly, such as dried and coiled strings of alimentary paste known as coil spaghetti, the articles are not uniformly distributed and supplied to the weighing machines only by the vibration of the distributing and supplying device. The articles are sometimes not sufficiently supplied to some weighing machines, resulting in lowered weighing accuracy of a weighing failure. One solution to this problem would be to operate the distributing and supplying device in a composite motion such as of vibration and vertical movement, or to construct the distributing and supplying device of a plurality of members actuatable in different motion patterns, for thereby preventing the articles from clinging to each other. However, such arrangements would be disadvantageous in that the drive mechanism for the distributing and supplying device would have to be much larger in size, making it difficult to position the distributing and supplying device in a limited space surrounded by the weighing machines.